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| United States Patent |
6,187,833
|
|
Oxman
, et al.
|
February 13, 2001
|
Ternary photoinitiator system for curing of epoxy/polyol resin composition
Abstract
Photocurable, addition polymerizable compositions contain an epoxy resin
and a photoinitiator system containing (a) an epoxy resin, (b) a hydroxyl
containing material and (c) a photoinitiator system comprising: (i) an
iodonium salt; (ii) a visible light sensitizer; and (iii) an electron
donor compound, wherein the photoinitiator system has a photoinduced
potential of at least about 100 mV relative to a standard solution of
2.9.times.10.sup.-5 moles/g diphenyl iodonium hexafluoroantimonate and
1.5.times.10.sup.-5 moles/g camphorquinone in 2-butanone. The compositions
cure on exposure to light in the visible spectrum and are useful in a
variety of applications, including dental adhesives and composites.
| Inventors:
|
Oxman; Joel D. (St. Louis Park, MN);
Jacobs; Dwight W. (Hudson, WI)
|
| Assignee:
|
3M Innovative Properties Company (St. Paul, MN)
|
| Appl. No.:
|
362621 |
| Filed:
|
July 28, 1999 |
| Current U.S. Class: |
522/15; 522/25; 522/81; 522/83; 522/146; 522/170; 522/908; 523/116; 523/117 |
| Intern'l Class: |
C08F 002/50; C08G 059/20; C08L 063/00 |
| Field of Search: |
522/15,25,146,170,908,100,103,81,83
523/116,117
|
References Cited
U.S. Patent Documents
| 3018262 | Jan., 1962 | Schroeder | 260/29.
|
| 3117099 | Jan., 1964 | Proops | 260/18.
|
| 3729313 | Apr., 1973 | Smith | 96/27.
|
| 3741769 | Jun., 1973 | Smith | 96/35.
|
| 3808006 | Apr., 1974 | Smith | 96/88.
|
| 4250053 | Feb., 1981 | Smith | 252/426.
|
| 4256828 | Mar., 1981 | Smith | 430/280.
|
| 4394403 | Jul., 1983 | Smith | 427/42.
|
| 4503169 | Mar., 1985 | Randklev | 523/117.
|
| 4642126 | Feb., 1987 | Zador | 51/295.
|
| 4652274 | Mar., 1987 | Boettcher | 51/298.
|
| 4695251 | Sep., 1987 | Randklev | 433/8.
|
| 4835193 | May., 1989 | Hayase | 522/15.
|
| 5545676 | Aug., 1996 | Palazzotto | 522/15.
|
| 5808108 | Sep., 1998 | Chappelow et al. | 549/335.
|
| 5998495 | Dec., 1999 | Oxman et al.
| |
| 6025406 | Feb., 2000 | Oxman et al.
| |
| Foreign Patent Documents |
| 290133 | Nov., 1988 | EP.
| |
| WO 95/14716 | Jun., 1995 | WO.
| |
| WO 96/13538 | May., 1996 | WO.
| |
Other References
Beringer et al., J. Am. Chem. Soc. 81,342 (1959).
Booklet entitled "Cyracure.RTM.Cycloaliphatic Epoxides," Union Carbide
Corporation 1995.
|
Primary Examiner: Berman; Susan W.
Parent Case Text
This is a continuation of application Ser. No. 08/840,093 filed Apr. 11,
1997, now U.S. Pat. No. 5,998,495.
Claims
We claim:
1. A photopolymerizable composition comprising:
(a) a blend of epoxy resins comprising:
(i) a cycloaliphatic epoxide; and
(ii) an epoxide that is different than the cycloaliphatic epoxide, and
which is selected from the group consisting of aliphatic epoxide, aromatic
epoxide, and mixtures thereof;
(b) a hydroxyl-containing material; and
(c) a photoinitiator system comprising:
(i) an iodonium salt;
(ii) a visible light sensitizer; and
(iii) an electron donor compound, wherein the photoinitiator system has a
photoinduced potential greater than or equal to that of
3-dimethylaminobenzoic acid in a standard solution of 2.9.times.10.sup.-5
moles/g diphenyl iodonium hexafluoroantimonate and 1.5.times.10.sup.-5
moles/g camphorquinone in 2-butanone.
2. The composition of claim 1 wherein the cycloaliphatic epoxide contains a
cyclohexene oxide group.
3. The composition of claim 1 wherein the aliphatic epoxide or aromatic
epoxide is selected from the group consisting of alkyl glycidyl ether,
aryl glycidyl ether, and mixtures thereof.
4. The composition of claim 3 wherein the aryl glycidyl ether is selected
from the group consisting of bisphenol A epoxides, bisphenol F epoxides,
and mixtures thereof.
5. The composition of claim 3 wherein the cycloaliphatic epoxide contains a
cyclohexene oxide group, and wherein the aliphatic epoxide or aromatic
epoxide is selected from the group consisting of alkyl glycidyl ether,
aryl glycidyl ether, and mixtures thereof.
6. The composition of claim 5 wherein the aryl glycidyl ether is selected
from the group consisting of bisphenol A epoxides, bisphenol F epoxides,
and mixtures thereof.
7. A photopolymerizable composition comprising:
(a) an epoxy resin;
(b) a hydroxyl-containing material; and
(c) a photoinitiator system comprising:
(i) an iodonium salt;
(ii) a visible light sensitizer; and
(iii) an electron donor compound, wherein the photoinitiator system has a
photoinduced potential greater than or equal to that of
3-dimethylaminobenzoic acid in a standard solution of 2.9.times.10.sup.-5
moles/g diphenyl iodonium hexafluoroantimonate and 1.5.times.10.sup.-5
moles/g camphorquinone in 2-butanone;
wherein the composition provides a photocurable adhesive or a photocurable
composite.
8. The composition of claim 7 further comprising a radiopaque filler.
9. A photopolymerizable composition comprising:
(a) an epoxy resin;
(b) a hydroxyl-containing material; and
(c) a photoinitiator system comprising:
(i) an iodonium salt;
(ii) a visible light sensitizer, and
(iii) an electron donor compound, wherein the photoinitiator system has a
photoinduced potential greater than or equal to that of
3-dimethylaminobenzoic acid in a standard solution of 2.9.times.10.sup.-5
moles/g diphenyl iodonium hexafluoroantimonate and 1.5.times.10.sup.-5
moles/g camphorquinone in 2-butanone;
wherein the composition is polymerizable into a dental prosthesis.
Description
FIELD OF THE INVENTION
The invention relates to photocurable, addition polymerizable compositions
that contain an epoxy resin, a hydroxyl containing material, and
optionally a free radically polymerizable material. The compositions
contain a ternary photoinitiator system that is activated on exposure to
actinic radiation in the visible spectrum. The invention is additionally
directed to methods of curing addition polymerizable compositions using
the ternary photoinitiator system.
BACKGROUND OF THE INVENTION
Epoxy containing compounds are known to be curable using various cationic
initiator systems. Smith, in U.S. Pat. No. 4,256,828, describes
photopolymerizable compositions that contain epoxides, an organic compound
with hydroxyl functionality, and a photosensitive aromatic sulfonium or
iodonium salt of a halogen containing complex ion. Hayase et al., U.S.
Pat. No. 4,835,193, describes photopolymerizable epoxy resin compositions
that comprise an epoxy resin and a heteropoly-acid aromatic sulfonium salt
as the photocuring catalyst. In WO 95/14716 Neckers et al. describe
photohardenable compositions that comprise a cationically polymerizable
compound, a xanthene or fluorone dye, a hydrogen donor, and an onium salt.
Palazzotto et al., U.S. Pat. No. 5,545,676, describes addition
polymerization of free-radically polymerizable materials. The
photoinitiator system described in that patent comprises an aryliodonium
salt, a sensitizer, and an electron donor having an oxidation potential
less than or equal to that of p-dimethoxybenzene.
PCT published application No. WO 96/13538 describes a system for curing
epoxy compounds by exposure to visible light by use of a system comprising
an aryliodonium salt and a sensitizer. Comparative Example 34 of this
disclosure describes the use of one of the initiator systems of Palazzotto
et al., U.S. Pat. No. 5,545,676 in an epoxy/polyol resin system. N,
N-dimethylbenzylamine is used as the electron donor. The results of this
experiment indicated that the use of this amine donor tended to retard the
cure of the resin system.
Suppliers of cationically cured resins expressly warn against using organic
amines in photoinitiated epoxy resins. An example of such a warning is
found in Union Carbide literature regarding Cyracure.RTM. cycloaliphatic
epoxides.
SUMMARY OF THE INVENTION
We have discovered, and the invention provides, a photopolymerizable
composition that contains an epoxy resin, a hydroxyl-functional compound
and a photoinitiator system containing an iodonium salt, a visible light
sensitizer, and an electron donor compound, wherein the photoinitiator
system has a photoinduced potential greater than or equal to that of
3-dimethylamino benzoic acid in a standard solution of 2.9.times.10.sup.-5
moles/g diphenyl iodonium hexafluoroantimonate and 1.5.times.10.sup.-5
moles/g camphorquinone in 2-butanone. Generally, 3-dimethylamino benzoic
acid in this standard exhibits a photoinduced potential of at least about
115 mV relative to a standard solution of 2.9.times.10.sup.-5 moles/g
diphenyl iodonium hexafluoroantimonate and 1.5.times.10.sup.-5 moles/g
camphorquinone in 2-butanone.
These compositions are curable on exposure to light having a wavelength of
about 400 to 1000 nm, and the invention provides a method of addition
photopolymerization comprising the step of irradiating a
photopolymerizable composition with light having a wavelength of about 400
to 1000 nm until the composition gels or hardens, the composition
containing an epoxy resin, a hydroxyl-containing material and a
photoinitiator system containing an iodonium salt, a visible light
sensitizer, and an electron donor compound wherein the photoinitiator
system has a photoinduced potential of at least about 100 mV relative to a
standard solution of 2.9.times.10.sup.-5 moles/g diphenyl iodonium
hexafluoroantimonate and 1.5.times.10.sup.-5 moles/g camphorquinone in
2-butanone.
In this application "polyol" and "hydroxyl-containing material" are used
interchangeably.
The initiator systems of the invention allow efficient cationic
polymerization under conditions of room temperature and standard pressure.
In addition, the initiator systems can, under appropriate conditions,
initiate both cationic and free-radical polymerization. This property
permits their use with a variety of photopolymerizable compositions,
including systems that contain acrylate or methacrylate functionality. Use
of the initiator systems of the invention can provide a substantial
reduction in the time required for an epoxy and hydroxyl containing resin
composition to cure to a tack-free gel or solid. This reduction in gel
time can represent about a 30 to 70% decrease in the time required for a
resin composition to harden to a tack-free gel or solid.
DETAILED DESCRIPTION OF THE INVENTION
The photopolymerizable compositions of the invention are sensitive
throughout the visible spectral region and photocure without the need to
introduce substantial heat to the system to initiate cure, although an
incidental amount of heat can be present. The term "visible light" is used
throughout this application to refer to light having a wavelength of about
400 to 1000 nanometers (nm). Photopolymerization of the compositions takes
place on exposure of the compositions to a source of actinic radiation
having a wavelength within this spectral region.
The cationically polymerizable epoxy resins useful in the compositions of
the invention are organic compounds having an oxirane ring, i.e., a up of
the formula
##STR1##
which is polymerizable by ring opening. Such materials, broadly called
epoxides, include monomeric epoxy compounds and epoxides of the polymeric
type and can be aliphatic, cycloaliphatic, aromatic or heterocyclic. These
materials generally have, on the average, at least 1 polymerizable epoxy
group per molecule, preferably at least about 1.5 and more preferably at
least about 2 polymerizable epoxy groups per molecule. The polymeric
epoxides include linear polymers having terminal epoxy groups (e.g., a
diglycidyl ether of a polyoxyalkylene glycol), polymers having skeletal
oxirane units (e.g., polybutadiene polyepoxide), and polymers having
pendent epoxy groups (e.g., a glycidyl methacrylate polymer or copolymer).
The epoxides may be pure compounds or may be mixtures of compounds
containing one, two, or more epoxy groups per molecule. The "average"
number of epoxy groups per molecule is determined by dividing the total
number of epoxy groups in the epoxy-containing material by the total
number of epoxy-containing molecules present.
These epoxy-containing materials may vary from low molecular weight
monomeric materials to high molecular weight polymers and may vary greatly
in the nature of their backbone and substituent groups. For example, the
backbone may be of any type and substituent groups thereon can be any
group that does not substantially interfere with cationic cure at room
temperature. Illustrative of permissible substituent groups include
halogens, ester groups, ethers, sulfonate groups, siloxane groups, nitro
groups, phosphate groups, and the like. The molecular weight of the
epoxy-containing materials may vary from about 58 to about 100,000 or
more.
Useful epoxy-containing materials include those which contain cyclohexene
oxide groups such as epoxycyclohexanecarboxylates, typified by
3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate,
3,4-epoxy-2-methylcyclohexylmethyl-3,4-epoxy-2-methylcyclohexane
carboxylate, and bis(3,4-epoxy-6-methylcyclohexylmethyl) adipate. For a
more detailed list of useful epoxides of this nature, reference is made to
the U.S. Pat. No. 3,117,099, which is incorporated herein by reference.
Further epoxy-containing materials which are useful in the compositions of
this invention include glycidyl ether monomers of the formula
##STR2##
where R' is alkyl or aryl and n is an integer of 1 to 6. Examples are
glycidyl ethers of polyhydric phenols obtained by reacting a polyhydric
phenol with an excess of chlorohydrin such as epichlorohydrin (e.g., the
diglycidyl ether of 2,2-bis-(2,3-epoxypropoxyphenol)-propane). Further
examples of epoxides of this type are described in U.S. Pat. No.
3,018,262, which is incorporated herein by reference, and in "Handbook of
Epoxy Resins" by Lee and Neville, McGraw-Hill Book Co., New York (1967).
There are a host of commercially available epoxy resins which can be used
in this invention. In particular, epoxides which are readily available
include octadecylene oxide, epichlorohydrin, styrene oxide, vinyl
cyclohexene oxide, glycidol, glycidylmethacrylate, diglycidyl ether of
Bisphenol A (e.g., those available under the trade designations "Epon
828", "Epon 825", "Epon 1004" and "Epon 1010" from Shell Chemical Co.,
"DER-331", "DER-332", and "DER-334", from Dow Chemical Co.),
vinylcyclohexene dioxide (e.g., "ERL-4206" from Union Carbide Corp.),
3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexene carboxylate (e.g.,
"ERL4221" or "CYRACURE UVR 6110" or UVR 6105" from Union Carbide Corp.),
3,4-epoxy-6-methylcyclohexylmethyl-3,4-epoxy-6-methyl-cyclohexene
carboxylate (e.g., "ERL-4201" from Union Carbide Corp.),
bis(3,4-epoxy-6-methylcyclohexylmethyl) adipate (e.g., "ERL-4289" from
Union Carbide Corp.), bis(2,3-epoxycyclopentyl) ether (e.g., "ERL-0400"
from Union Carbide Corp.), aliphatic epoxy modified from polypropylene
glycol (e.g., "ERL-4050" and "ERL-4052" from Union Carbide Corp.),
dipentene dioxide (e.g., "ERL-4269" from Union Carbide Corp.), epoxidized
polybutadiene (e.g., "Oxiron 2001" from FMC Corp.), silicone resin
containing epoxy functionality, flame retardant epoxy resins (e.g.,
"DER-580", a brominated bisphenol type epoxy resin available from Dow
Chemical Co.), 1,4-butanediol diglycidyl ether of phenolformaldehyde
novolak (e.g., "DEN-431" and "DEN-438" from Dow Chemical Co.), and
resorcinol diglycidyl ether (e.g., "Kopoxite" from Koppers Company, Inc.),
bis(3,4-epoxycyclohexyl)adipate (e.g., "ERL-4299" or "UVR-6128", from
Union Carbide Corp.), 2-(3,4-epoxycyclohexyl-5, 5-spiro-3,4-epoxy)
cyclohexane-meta-dioxane (e.g., "ERL-4234" from Union Carbide Corp.),
vinylcyclohexene monoxide 1,2-epoxyhexadecane (e.g., "UVR-6216" from Union
Carbide Corp.), alkyl glycidyl ethers such as alkyl C.sub.8 -C.sub.10
glycidyl ether (e.g., "HELOXY Modifier 1" from Shell Chemical Co.), alkyl
C.sub.12 -C.sub.14 glycidyl ether (e.g., "HELOXY Modifier 8" from Shell
Chemical Co.), butyl glycidyl ether (e.g., "HELOXY Modifier 61" from Shell
Chemical Co.), cresyl glycidyl ether (e.g., "HELOXY Modifier 62" from
Shell Chemical Co.), p-ter butylphenyl glycidyl ether (e.g., "HELOXY
Modifier 65" from Shell Chemical Co.), polyfunctional glycidyl ethers such
as diglycidyl ether of 1,4-butanediol (e.g., "HELOXY Modifier 67" from
Shell Chemical Co.), diglycidyl ether of neopentyl glycol (e.g., "HELOXY
Modifier 68" from Shell Chemical Co.), diglycidyl ether of
cyclohexanedimethanol (e.g., "HELOXY Modifier 107" from Shell Chemical
Co.), trimethylol ethane triglycidyl ether (e.g., "HELOXY Modifier 44"
from Shell Chemical Co.), trimethylol propane triglycidyl ether (e.g.,
"HELOXY Modifier 48" from Shell Chemical Co.), polyglycidyl ether of an
aliphatic polyol (e.g., "HELOXY Modifier 84" from Shell Chemical Co.),
polyglycol diepoxide (e.g., "HELOXY Modifier 32" from Shell Chemical Co.),
bisphenol F epoxides (e.g., "EPN-1138" or "GY-281" from Ciba-Geigy Corp.),
9,9-bis[4-(2,3-epoxypropoxy)-phenyl]fluorenone (e.g., "Epon 1079" from
Shell Chemical Co.).
Still other epoxy resins contain copolymers of acrylic acid esters or
glycidol such as glycidylacrylate and glycidylmethacrylate with one or
more copolymerizable vinyl compounds. Examples of such copolymers are 1:1
styrene-glycidylmethacrylate, 1:1 methylmethacrylate-glycidylacrylate and
a 62.5:24:13.5 methylmethacrylate-ethyl acrylate-glycidylmethacrylate.
Other useful epoxy resins are well known and contain such epoxides as
epichlorohydrins, alkylene oxides, e.g., propylene oxide, styrene oxide;
alkenyl oxides, e.g., butadiene oxide; glycidyl esters, e.g., ethyl
glycidate.
The polymers of the epoxy resin can optionally contain other
functionalities that do not substantially interfere with cationic cure at
room temperature.
Blends of various epoxy-containing materials are also contemplated in this
invention. Examples of such blends include two or more weight average
molecular weight distributions of epoxy-containing compounds, such as low
molecular weight below 200), intermediate molecular weight (about 200 to
10,000) and higher molecular weight (above about 10,000). Alternatively or
additionally, the epoxy resin may contain a blend of epoxy-containing
materials having different chemical natures, such as aliphatic and
aromatic, or functionalities, such as polar and non-polar. Other
cationically polymerizable polymers can additionally be incorporated, such
as vinyl ethers, etc., if desired.
The hydroxyl-containing material which is used in the present invention can
be any organic material having hydroxyl functionality of at least 1, and
preferably at least 2.
Preferably the hydroxyl-containing material contains two or more primary or
secondary aliphatic hydroxyl groups (i.e., the hydroxyl group is bonded
directly to a non-aromatic carbon atom). The hydroxyl groups can be
terminally situated, or they can be pendent from a polymer or copolymer.
The molecular weight of the hydroxyl-containing organic material can vary
from very low (e.g., 32) to very high (e.g., one million or more).
Suitable hydroxyl-containing materials can have low molecular weights,
i.e. from about 32 to 200, intermediate molecular weight, i.e. from about
200 to 10,000, or high molecular weight, i.e. above about 10,000. As used
herein, all molecular weights are weight average molecular weights.
The hydroxyl-containing material can optionally contain other
functionalities that do not substantially interfere with cationic cure at
room temperature. Thus, the hydroxyl-containing materials can be
nonaromatic in nature or can contain aromatic functionality. The
hydroxyl-containing material can optionally contain heteroatoms in the
backbone of the molecule, such as nitrogen, oxygen, sulfur, and the like,
provided that the ultimate hydroxyl-containing material does not
substantially interfere with cationic cure at room temperature. The
hydroxyl-containing material can, for example, be selected from naturally
occurring or synthetically prepared cellulosic materials. Of course, the
hydroxyl-containing material is also substantially free of groups which
may be thermally or photolytically unstable; that is, the material will
not decompose or liberate volatile components at temperatures below about
100.degree. C. or in the presence of actinic light which may be
encountered during the desired curing conditions for the
photocopolymerizable composition.
Representative examples of suitable hydroxyl-containing materials having a
hydroxyl functionality of 1 include alkanols, monoalkyl ethers of
polyoxyalkyleneglycols, monoalkyl ethers of alkylene-glycols, and others
known in the art.
Representative examples of useful monomeric polyhydroxy organic materials
include alkylene glycols (e.g., 1,2-ethanediol; 1,3-propanediol;
1,4-butanediol; 1,6-hexanediol; 1,8-octanediol; 2-ethyl-1,6-hexanediol;
bis(hydroxymethyl)cyclohexane; 1,18-dihydroxyoctadecane;
3-chloro-1,2-propanediol); polyhydroxyalkanes (e.g., glycerine,
tri-methylolethane, pentaerythritol, sorbitol) and other polyhydroxy
compounds such as N,N-bis(hydroxyethyl)benzamide; 2-butyne-1,4-diol;
4,4-bis(hydroxymethyl)diphenylsulfone; castor oil; and the like.
Representative examples of useful polymeric hydroxyl-containing materials
include polyoxyethylene and polyoxypropylene glycols, and particularly the
polyoxyethylene and polyoxypropylene glycol diols and triols having
molecular weights from about 200 to about 10,000 corresponding to a
hydroxy equivalent weight of 100 to 5000 for the diols or 70 to 3300 for
triols; polytetramethylene ether glycols such as polytetrahydrofuran or
"poly THF" of varying molecular weight; copolymers of hydroxypropyl and
hydroxyethyl acrylates and methacrylates with other free
radical-polymerizable monomers such as acrylate esters, vinyl halides, or
styrene; copolymers containing pendent hydroxy groups formed by hydrolysis
or partial hydrolysis of vinyl acetate copolymers, polyvinylacetal resins
containing pendent hydroxyl groups; modified cellulose polymers such as
hydroxyethylated and hydroxypropylated cellulose; hydroxy-terminated
polyesters; hydroxy-terminated polylactones, and particularly the
polycaprolactones; fluorinated polyoxyethylene or polyoxypropylene
glycols; and hydroxy-terminated polyalkadienes.
Useful commercially available hydroxyl-containing materials include the
"TERATHANE" series of polytetramethylene ether glycols such as "TERATHANE"
650, 1000, 2000 and 2900 (available from du Pont de Nemours, Wilmington,
Del.) the "PEP" series of polyoxyalkylene tetrols having secondary
hydroxyl groups such as "PEP" 450, 550 and 650; "BUTVAR" series of
polyvinylacetal resins such as "BUTVAR" B-72A, B-73, B-76, B-90 and B-98
(available from Monsanto Chemical Company, St. Louis, Mo.); and the
"FORMVAR" series of resins such as 7/70, 12/85, 7/95S, 7/95E, 15/95S and
15/95E (available from Monsanto Chemical Company); the "TONE" series of
polycaprolactone polyols such as "TONE" 0200, 0210, 0230,0240, 0300 and
0301 (available from Union Carbide); "PARAPLEX U-148" aliphatic polyester
diol (available from Rohm and Haas, Philadelphia, Pa.), the "MULTRON" R
series of saturated polyester polyols such as "MULTRON" R-2, R-12A, R-16,
R-18, R-38, R-68 and R-74 (available from Mobay Chemical Co.); "KLUCEL E"
hydroxypropylated cellulose having an equivalent weight of approximately
100 (available from Hercules Inc.); "Alcohol Soluble Butyrate" cellulose
acetate butyrate ester having a hydroxyl equivalent weight of
approximately 400 (available from Eastman Kodak Co., Rochester, N.Y.);
polyether polyols such as polypropylene glycol diol (e.g., "ARCOL
PPG-425", "Arcol PPG-725", "ARCOL PPG-1025", "ARCOL PPG-2025", ARCOL
PPG-3025", "ARCOL PPG-4025" from ARCO Chemical Co.); polypropylene glycol
triol (e.g., "ARCOL LT-28", "ARCOL LHT-42", "ARCOL LHT 112", "ARCOL LHT
240", "ARCOL LG-56", "ARCOL LG-168", "ARCOL LG-650" from ARCO Chemical
Co.); ethylene oxide capped polyoxypropylene triol or diol (e.g., "ARCOL
11-27", "ARCOL 11-34", "ARCOL E-351", "ARCOL E-452", "ARCOL E-785", "ARCOL
E-786" from ARCO Chemical Co.); ethoxylated bis-phenol A; propylene oxide
or ethylene oxide - based polyols (e.g., "VORANOL" polyether polyols from
the Dow Chemical Co.).
The amount of hydroxyl-containing organic material used in the compositions
of the invention may vary over broad ranges, depending upon factors such
as the compatibility of the hydroxyl-containing material with the epoxide,
the equivalent weight and functionality of the hydroxyl-containing
material, the physical properties desired in the final cured composition,
the desired speed of photocure, and the like.
Blends of various hydroxyl-containing materials are particularly
contemplated in this invention. Examples of such blends include two or
more molecular weight distributions of hydroxyl-containing compounds, such
as low molecular weight (below 200), intermediate molecular weight (about
200 to 10,000) and higher molecular weight ( above about 10,000).
Alternatively or additionally, the hydroxyl-containing material can
contain a blend of hydroxyl-containing materials having different chemical
natures, such as aliphatic and aromatic, or functionalities, such as polar
and non-polar. As an additional example, one may use mixtures of two or
more poly-functional hydroxy materials or one or more mono-functional
hydroxy materials with poly-functional hydroxy materials.
If desired, the composition can also contain a free-radically polymerizable
material, including one or more ethylenically unsaturated monomer,
monomers, oligomers or polymers. Suitable materials contain at least one
ethylenically unsaturated bond, and are capable of undergoing addition
polymerization. Such free radically polymerizable materials include mono-,
di- or poly- acrylates and methacrylates such as methyl acrylate, methyl
methacrylate, ethyl acrylate, isopropyl methacrylate, n-hexyl acrylate,
stearyl acrylate, allyl acrylate, glycerol diacrylate, glycerol
triacrylate, ethyleneglycol diacrylate, diethyleneglycol diacrylate,
triethyleneglycol dimethacrylate, 1,3-propanediol diacrylate,
1,3-propanediol dimethacrylate, trimethylolpropane triacrylate,
1,2,4-butanetriol trimethacrylate, 1,4-cyclohexanediol diacrylate,
pentaerythritol triacrylate, pentaerythritol tetraacrylate,
pentaerythritol tetramethacrylate, sorbitol hexacrylate,
bis[1-(2-acryloxy)]-p-ethoxyphenyldimethylmethane,
bis[1-(3-acryloxy-2-hydroxy)]-p-propoxyphenyldimethylmethane, and
trishydroxyethyl-isocyanurate trimethacrylate; the bis-acrylates and
bis-methacrylates of polyethylene glycols of molecular weight 200-500,
copolymerizable mixtures of acrylated monomers such as those in U.S. Pat.
No. 4,652,274, and acrylated oligomers such as those of U.S. Pat. No.
4,642,126; and vinyl compounds such as styrene, diallyl phthalate, divinyl
succinate, divinyl adipate and divinylphthalate. Mixtures of two or more
of these free radically polymerizable materials can be used if desired.
If desired, the polymerizable material(s) may contain both epoxy and
free-radically polymerizable functionalities in a single molecule. These
may be obtained by reacting a di- or poly-epoxide with one or more
equivalents of an ethylenically unsaturated carboxylic acid. An example of
such a material is the reaction product of UVR-6105 (available from Union
Carbide) with one equivalent of methacrylic acid. Commercially available
materials having epoxy and free-radically polymerizable functionalities
include the "Cyclomer" series, such as Cyclomer M100 or M101, available
from Daicel Chemical, Japan.
The polymerizable material(s) can also contain hydroxyl and free radically
polymerizable functionalities in a single molecule. Examples of such
materials include hydroxyalkylacrylates and hydroxyalkylmethacrylates such
as hydroxyethylacrylate, hydroxyethylmethacrylate; glycerol mono- or
di-acrylate and methacrylate; and the like.
The epoxy resin, hydroxyl-containing material and optional free radically
polymerizable material(s) are combined with a three component or ternary
photoinitiator system. Three component initiator systems are described in
Palazzotto et al., U.S. Pat. No. 5,545,676, which is incorporated herein
by reference. The first component in the photoinitiator system is an
iodonium salt, i.e., a diaryliodonium salt. The iodonium salt should be
soluble in the monomer and preferably is shelf-stable, meaning it does not
spontaneously promote polymerization when dissolved therein in the
presence of the sensitizer and donor. Accordingly, selection of a
particular iodonium salt may depend to some extent upon the particular
monomer, sensitizer and donor chosen. Suitable iodonium salts are
described in U.S. Pat. Nos. 3,729,313, 3,741,769, 3,808,006, 4,250,053 and
4,394,403, the iodonium salt disclosures of which are incorporated herein
by reference. The iodonium salt can be a simple salt, containing an anion
such as Cl.sup.--, Br.sup.--, I.sup.-- or C.sub.4 H.sub.5 SO.sub.3.sup.--
; or a metal complex salt containing an antimonate, arsenate, phosphate or
borate such as SbF.sub.5 OH.sup.-- or AsF.sub.6.sup.--. Mixtures of
iodonium salts can be used if desired.
Examples of useful aromatic iodonium complex salt photoinitiators include:
diphenyliodonium tetrafluoroborate; di(4-methylphenyl)iodonium
tetrafluoroborate; phenyl-4-methylphenyliodonium tetrafluoroborate;
di(4-heptylphenyl)iodonium tetrafluoroborate; di(3-nitrophenyl)iodonium
hexafluorophosphate; di(4-chlorophenyl)iodonium hexafluorophosphate;
di(naphthyl)iodonium tetrafluoroborate;
di(4-trifluoromethylphenyl)iodonium tetrafluoroborate; diphenyliodonium
hexafluorophosphate; di(4-methylphenyl)iodonium hexafluorophosphate;
diphenyliodonium hexafluoroarsenate; di(4-phenoxyphenyl)iodonium
tetrafluoroborate; phenyl-2-thienyliodonium hexafluorophosphate;
3,5-dimethylpyrazolyl-4-phenyliodonium hexafluorophosphate;
diphenyliodonium hexafluoroantimonate; 2,2'-diphenyliodonium
tetrafluoroborate; di(2,4-dichlorophenyl)iodonium hexafluorophosphate;
di(4-bromophenyl)iodonium hexafluorophosphate; di(4-methoxyphenyl)iodonium
hexafluorophosphate; di(3-carboxyphenyl)iodonium hexafluorophosphate;
di(3-methoxycarbonylphenyl)iodonium hexafluorophosphate;
di(3-methoxysulfonylphenyl)iodonium hexafluorophosphate;
di(4-acetamidophenyl)iodonium hexafluorophosphate;
di(2-benzothienyl)iodonium hexafluorophosphate; and diphenyliodonium
hexafluoroantimonate.
Of the aromatic iodonium complex salts which are suitable for use in the
compositions of the invention diaryliodonium hexafluorophosphate and
diaryliodonium hexafluoroantimonate are among the preferred salts. These
salts are preferred because, in general, they promote faster reaction, and
are more soluble in inert organic solvents than are other aromatic
iodonium salts of complex ions.
The aromatic iodonium complex salts may be prepared by metathesis of
corresponding aromatic iodonium simple salts (such as, for example,
diphenyliodonium bisulfate) in accordance with the teachings of Beringer
et al., J. Am. Chem. Soc. 81,342 (1959). Thus, for example, the complex
salt diphenyliodonium tetrafluoroborate is prepared by the addition at
60.degree. C. of an aqueous solution containing 29.2 g silver
fluoroborate, 2 g fluoroboric acid, and 0.5 g phosphorous acid in about 30
ml of water to a solution of 44 g (139 millimoles) of diphenyliodonium
chloride. The silver halide that precipitates is filtered off and the
filtrate concentrated to yield diphenyliodonium fluoroborate which may be
purified by recrystallization.
The aromatic iodonium simple salts may be prepared in accordance with
Beringer et al., above, by various methods including (1) coupling of two
aromatic compounds with iodyl sulfate in sulfuric acid, (2) coupling of
two aromatic compounds with an iodate in acetic acid-acetic
anhydride-sulfuric acid, (3) coupling of two aromatic compounds with an
iodine acrylate in the presence of an acid, and (4) condensation of an
iodoso compound, an iodoso diacetate, or an iodoxy compound with another
aromatic compound in the presence of an acid. Diphenyliodonium bisulfate
is prepared by method (3), for example, by the addition over a period of
eight hours at below 5.degree. C. of a mixture of 35 ml of conc. sulfuric
acid and 50 ml of acetic anhydride to a well-stirred mixture of 55.5 ml of
benzene, 50 ml of acetic anhydride, and 53.5 g of potassium iodate. The
mixture is stirred for an additional four hours at 0.degree.-5.degree. C.
and at room temperature (about 25.degree. C.) for 48 hours and treated
with 300 ml of diethyl ether. On concentration, crude diphenyliodonium
bisulfate precipitates and may be purified by recrystallization if
desired.
The second component in the photoinitiator system is the sensitizer. The
sensitizer should be soluble in the photopolymerizable composition, free
of functionalities that would substantially interfere with the cationic
curing process, and capable of light absorption within the range of
wavelengths between about 300 and about 1000 nanometers.
Suitable sensitizers include compounds in the following categories:
ketones, coumarin dyes (e.g., ketocoumarins), xanthene dyes, acridine
dyes, thiazole dyes, thiazine dyes, oxazine dyes, azine dyes, aminoketone
dyes, porphyrins, aromatic polycyclic hydrocarbons, p-substituted
aminostyryl ketone compounds, aminotriaryl methanes, merocyanines,
squarylium dyes and pyridinium dyes. Ketones (e.g., monoketones or
alpha-diketones), ketocoumarins, aminoarylketones and p-substituted
aminostyryl ketone compounds are preferred sensitizers. For applications
requiring deep cure (e.g., cure of highly-filled composites), it is
preferred to employ sensitizers having an extinction coefficient below
about 1000 1 mole.sup.-1 cm.sup.-1, more preferably about or below 100 1
mole.sup.-1 cm.sup.-1, at the desired wavelength of irradiation for
photopolymerization. The alpha-diketones are an example of a class of
sensitizers having this property, and are particularly preferred for
dental applications.
By way of example, a preferred class of ketone sensitizers has the formula:
ACO(X).sub.b B
where X is CO or CR.sup.1 R.sup.2 where R.sup.1 and R.sup.2 can be the same
different, and can be hydrogen, alkyl, alkaryl or aralkyl, b is zero, and
A and B can be the same or different and can be substituted (having one or
more non-interfering substituents) or unsubstituted aryl, alkyl, alkaryl,
or aralkyl groups, or together A and B can form a cyclic structure which
can be a substituted or unsubstituted cycloaliphatic, aromatic,
heteroaromatic or fused aromatic ring.
Suitable ketones of the above formula include monoketones (b=0) such as
2,2-, 4,4- or 2,4-dihydroxybenzophenone, di-2-pyridyl ketone, di-2-furanyl
ketone, di-2-thiophenyl ketone, benzoin, fluorenone, chalcone, Michler's
ketone, 2-fluoro-9-fluorenone, 2-chlorothioxanthone, acetophenone,
benzophenone, 1- or 2-acetonaphthone, 9-acetylanthracene, 2-, 3- or
9-acetylphenanthrene, 4-acetylbiphenyl, propiophenone, n-butyrophenone,
valerophenone, 2-, 3- or 4-acetylpyridine, 3-acetylcoumarin and the like.
Suitable diketones include aralkyldiketones such as anthraquinone,
phenanthrenequinone, o-, m- and p-diacetylbenzene, 1,3-, 1,4-, 1,5-, 1,6-,
1,7- and 1,8-diacetylnaphthalene, 1,5-, 1,8- and 9,10-diacetylanthracene,
and the like. Suitable 1-diketones (b=1 and X=CO) include 2,3-butanedione,
2,3-pentanedione, 2,3-hexanedione, 3,4-hexanedione, 2,3-heptanedione,
3,4-heptanedione, 2,3-octanedione, 4,5-octanedione, benzil, 2,2'-3 3'- and
4,4'-dihydroxylbenzil, furil, di-3,3'-indolylethanedione, 2,3-bornanedione
(camphorquinone), biacetyl, 1,2-cyclohexanedione, 1,2-naphthaquinone,
acenaphthaquinone, and the like.
Examples of particularly preferred visible light sensitizers include
camphorquinone; glyoxal; biacetyl; 3,3,6,6-tetramethylcyclohexanedione;
3,3,7,7-tetramethyl-1,2-cycloheptanedione;
3,3,8,8-tetramethyl-1,2-cyclooctanedione;
3,3,18,18-tetramethyl-1,2-cyclooctadecanedione; dipivaloyl; benzil; furil;
hydroxybenzil; 2,3-butanedione; 2,3-pentanedione; 2,3-hexanedione;
3,4-hexanedione; 2,3-heptanedione; 3,4-heptanedione; 2,3-octanedione;
4,5-octanedione; and 1,2-cyclohexanedione. Of these, camphorquinone is the
most highly preferred sensitizer.
The third component of the initiator system is an electron donor. The
electron donor compound(s) should meet the requirements set forth below
and be soluble in the polymerizable composition. The donor can also be
selected in consideration of other factors, such as shelf stability and
the nature of the polymerizable materials, iodonium salt and sensitizer
chosen. A class of donor compounds that may be useful in the inventive
systems may be selected from some of the donors described in Palazzotto et
al., U.S. Pat. No. 5,545,676. Possible donor compounds that meet the
criteria set forth by Palazzotto et al. must then be tested using one or
both of the methods set forth below to determine if they will be useful
donors for the photopolymerizable compositions of the invention.
The donor is typically an alkyl aromatic polyether or an alkyl, aryl amino
compound wherein the aryl group is substituted by one or more electron
withdrawing groups. Examples of suitable electron withdrawing groups
include carboxylic acid, carboxylic acid ester, ketone, aldehyde, sulfonic
acid, sulfonate and nitrile groups.
The suitability of a compound for use as an electron donor in the
compositions of the invention may be determined by measuring the
photoinduced potential of a sample photoinitiator system that includes the
compound. The photoinduced potential can be evaluated in the following
manner. A standard solution is prepared that contains 2.9.times.10.sup.-5
moles/g of diphenyl iodonium hexafluoroantimonate and 1.5.times.10.sup.-5
moles/g of camphorquinone in 2-butanone. A pH electrode is then immersed
in the solution and a pH meter is calibrated to zero mV. A test solution
of the standard solution and the compound is prepared next using the
compound at a concentration of 2.9.times.10.sup.-5 moles/g. This test
solution is irradiated using blue light having a wavelength of about 400
to 500 nm having an intensity of about 200 to 400 mW/cm.sup.2 for about 5
to 10 seconds at a distance of about 1 mm. Millivolts relative to the
standard solution are then determined by immersing the pH electrode in the
test solution and obtaining a mV reading on the pH meter. Useful donors
are those compounds that provide a reading of at least 100 mV relative to
the standard solution, and preferably provide a gel time for the
compositions that is at least about 30 to 40 percent shorter than for
compositions that do not contain the donor. Higher mV readings are
generally indicative of greater activity.
In some instances there may be some uncertainty regarding the outcome of
the above procedure. This may be due to questions or uncertainty arising
from the instrumentation employed, from the way the procedure was carried
out, or other factors, or one may wish to verify the suitability of a
particular compound. A second test may be performed to verify the result
obtained by following the above procedure and resolve any such
uncertainty.
The second method involves the evaluation of the photoinduced potential of
an initiator system that includes the compound compared to a system that
includes 3-dimethylamino benzoic acid. For this method, a standard
solution of 2.9.times.10.sup.-5 moles/g diphenyl iodonium
hexafluoroantimonate, 1.5.times.10.sup.-5 moles/g camphorquinone and
2.9.times.10.sup.-5 moles/g of 3-dimethylaminobenzoic acid in 2-butanone
is prepared. A pH electrode is then immersed in the solution and a pH
meter is calibrated to zero mV. The standard solution is irradiated with
blue light having a wavelength of between about 400-500 nm and an
intensity of about 200 to 400 mW/cm.sup.2 for about 5 to 10 seconds using
a focused light source such as a dental curing light at a distance of
about 1 mm. After light exposure, the potential of the solution is
measured by immersing a pH electrode in the irradiated standard solution
and reading the potential in mV using a pH meter. A test solution is then
prepared using 2.9.times.10.sup.-5 moles/g of diphenyl iodonium
hexafluoroantimonate, 1.5.times.10.sup.-5 moles/g of camphorquinone and
2.9.times.10.sup.-5 moles/g of the compound in 2-butanone. The test
solution is irradiated and the photoinduced potential measured using the
same technique as described for the standard solution. If the test
solution has a photoinduced potential that is the same as or greater than
that of the 3-dimethylaminobenzoic acid containing standard solution, then
the compound is a useful donor.
A preferred group of alkyl, aryl amine donor compounds is described by the
following structural formula:
##STR3##
wherein R.sup.1 are independently H, C.sub.1-18 alkyl that is optionally
substituted by one or more halogen, --CN, --OH, --SH, C.sub.1-18 alkoxy,
C.sub.1-18 alkylthio, C.sub.3-18 cycloalkyl, aryl, COOH, COOC.sub.1-18
alkyl, (C.sub.1-18 alkyl).sub.0-1 --CO--C.sub.1-18 alkyl, SO.sub.3
R.sup.2, CN or or aryl that is optionally substituted by one or more
electron withdrawing groups or the R.sup.1 groups may be joined to form a
ring; and Ar is aryl that is substituted by one or more electron
withdrawing groups. Suitable electron withdrawing groups include --COOH,
--COOR.sup.2, --SO.sub.3 R.sup.2, --CN, --CO--C.sub.1-18 alkyl and --C(O)H
groups.
A preferred group of aryl alkyl polyethers has the following structural
formula:
##STR4##
wherein n=1-3 each R.sub.3 is independently H or C.sub.1-18 alkyl that is
optionally substituted by one or more halogen, --CN, --OH, --SH,
C.sub.1-18 alkoxy, C.sub.1-18 alkylthio, C.sub.3-18 cycloalkyl, aryl,
substituted aryl, --COOH, --COOC.sub.1-18 alkyl, --(C.sub.1-18
alkyl).sub.0-1 --COH, --(C.sub.1-18 alkyl).sub.0-1 --CO--C.sub.1-18 alkyl,
--CO--C.sub.1-18 is alkyl, --C(O)H or --C.sub.2-18 alkenyl groups and each
R.sub.4 can be C.sub.1-18 alkyl that is optionally substituted by one or
more halogen, --CN, --OH, --SH, C.sub.1-18 alkoxy, C.sub.1-18 alkylthio,
C.sub.3-18 cycloalkyl, aryl, substituted aryl, --COOH, --COOC.sub.1-18
alkyl, --(C.sub.1-18 alkyl).sub.0-1 --COH, --(C.sub.1-18 alkyl).sub.0-1
--CO--C.sub.1-18 alkyl, --CO--C.sub.1-18 alkyl, --C(O)H or --C.sub.2-18
alkenyl groups.
In each of the above formulas the alkyl groups can be straight-chain or
branched, and the cycloalkyl group preferably has 3 to 6 ring carbon atoms
but may have additional alkyl substitution up to the specified number of
carbon atoms. The aryl groups may be carbocyclic or heterocyclic aryl, but
are preferably carbocyclic and more preferably phenyl rings.
Preferred donor compounds include 4-dimethylaminobenzoic acid, ethyl
4-dimethylaminobenzoate, 3-dimethylaminobenzoic acid,
4-dimethylaminobenzoin, 4-dimethylaminobenzaldehyde,
4-dimethylaminobenzonitrile and 1,2,4-trimethoxybenzene.
The photoinitiator compounds are provided in an amount effective to
initiate or enhance the rate of cure of the resin system. It has been
found that the amount of donor that is used can be critical particularly
when the donor is an amine. Too much donor can be deleterious to cure
properties. Preferably, the sensitizer is present in about 0.05-5 weight
percent based on resin compounds of the overall composition. More
preferably, the sensitizer is present at 0.10-1.0 weight percent.
Similarly, the iodonium initiator is preferably present at 0.05-10.0
weight percent, more preferably at 0.1-5.0 weight percent, and most
preferably 0.50-3.0 weight percent. Likewise, the donor is preferably
present at 0.01-5.0 weight percent, more preferably 0.05-1.0 weight
percent, and most preferably 0.05-0.50 weight percent.
The photopolymerizable compositions of the invention are prepared by simply
admixing, under "safe light" conditions, the components of the inventive
compositions. Suitable inert solvents may be employed if desired when
effecting this mixture. Any solvent may be used which does not react
appreciably with the components of the inventive compositions. Examples of
suitable solvents include acetone, dichloromethane, and acetonitrile. A
liquid material to be polymerized may be used as a solvent for another
liquid or solid material to be polymerized. Solventless compositions can
be prepared by simply dissolving the aromatic iodonium complex salt and
sensitizer in the epoxy resin polyol mixture with or without the use of
mild heating to facilitate dissolution.
The compositions of the present invention provide a very useful combination
of cure speed, cure depth and shelf life. They cure well even when loaded
with large amounts of fillers, and can be used in a variety of
applications including graphic arts imaging (e.g. for color proofing
systems, curable inks, or silverless imaging), printing plates (e.g.
projection plates or laser plates), photoresists, solder masks, electronic
conformal coatings, coated abrasives, magnetic media, photocurable
adhesives (e.g. for orthodontics) and photocurable composites (e.g., for
autobody repair or dentistry).
Dental applications particularly benefit from the unique compositions of
the present invention. Until now, acrylate and methacrylate chemistry has
been used extensively for adhesive and restorative dental compositions.
This chemistry has the advantage of being curable with visible light using
photoinitiator systems, but has the disadvantage of undergoing a
relatively high degree of shrinkage during the polymerization process. In
contrast, during polymerization the epoxy resins found in the compositions
of the present invention shrink significantly less than the acrylate and
methacrylate resins of the prior art. The present invention provides a
system for curing epoxy/polyol resin systems, with or without the presence
of an acrylate or methacrylate in an acceptable time frame and to a
sufficient depth using visible light source equipment already available in
the dental office.
The dental materials may be filled or unfilled and include dental materials
such as direct esthetic restorative materials (e.g., anterior and
posterior restoratives), prostheses, adhesives and primers for oral hard
tissues, sealants, veneers, cavity liners, orthodontic bracket adhesives
for use with any type of bracket (such as metal, plastic and ceramic),
crown and bridge cements, artificial crowns, artificial teeth, dentures,
and the like. These dental materials are used in the mouth and are
disposed adjacent to natural teeth. The phrase "disposed adjacent to" as
used herein refers to the placing of a dental material in temporary or
permanent bonding (e.g., adhesive) or touching (e.g., occlusal or
proximal) contact with a natural tooth. The term "composite" as used
herein refers to a filled dental material. The term "restorative" as used
herein refers to a composite which is polymerized after it is disposed
adjacent to a tooth. The term "prosthesis" as used herein refers to a
composite which is shaped and polymerized for its final use (e.g., as
crown, bridge, veneer, inlay, onlay or the like) before it is disposed
adjacent to a tooth. The term "sealant" as used herein refers to a lightly
filled composite or to an unfilled dental material which is cured after it
is disposed adjacent to a tooth. "Polymerizable" refers to curing or
hardening the dental material, e.g., by free-radical, cationic or mixed
reaction mechanisms.
In certain applications, the use of a filler may be appropriate. The choice
of filler affects important properties of the composite such as its
appearance, radiopacity and physical and mechanical properties. Appearance
is affected in part by adjustment of the amounts and relative refractive
indices of the ingredients of the composite, thereby allowing alteration
of the translucence, opacity or pearlescence of the composite. Epoxy resin
compositions of the invention, either alone or in admixture with diluent
monomer, can be prepared with refractive indices which approach or
approximate the refractive indices of fillers such as quartz (refractive
index 1.55), submicron silica (refractive index 1.46), and 5.5:1 mole
ratio SiO:ZrO, non-vitreous microparticles (refractive index 1.54). In
this way the appearance of the dental material can, if desired, be made to
closely approximate the appearance of natural dentition.
Radiopacity is a measurement of the ability of the composite to be detected
by x-ray examination. Frequently a radiopaque composite will be desirable,
for instance, to enable the dentist to determine whether or not a dental
restoration remains sound. Under other circumstances a non-radiopaque
composite may be desirable.
The amount of filler which is incorporated into the composite, referred to
herein as the "loading level" and expressed as a weight percent based on
the total weight of the dental material, will vary depending on the type
of filler, the epoxy resin and other components of the composition, and
the end use of the composite.
For some dental materials, such as sealants, the epoxy resin compositions
of the invention can be lightly filled (e.g., having a loading level of
less than about 40 weight percent) or unfilled. Preferably the viscosity
of the dental material is sufficiently low to allow its penetration into
pits and fissures of occlusal tooth surfaces as well as into etched areas
of enamel, thereby aiding in the retention of the dental material. In
applications where high strength or durability are desired (e.g., anterior
or posterior restoratives, prostheses, crown and bridge cements,
artificial crowns, artificial teeth and dentures) the loading level can be
as high as about 95 weight percent. For most dental restorative and
prosthetic applications a loading level of between about 70 and 90 weight
percent is generally preferred.
Fillers may be selected from one or more of any material(s) suitable for
incorporation in compositions used for medical applications, such as
fillers currently used in dental restorative compositions and the like.
The filler is finely divided and preferably has a maximum particle
diameter of less than about 50 micrometers and an average particle
diameter of less than about 10 micrometers. The filler can have a unimodal
or polymodal (e.g., bimodal) particle size distribution. The filler can be
an inorganic material. It can also be a crosslinked organic material that
is insoluble in the polymerizable resin, and is optionally filled with
inorganic filler. The filler should in any event be non-toxic and suitable
for use in the mouth. The filler can be radiopaque, radiolucent or
nonradiopaque.
Examples of suitable inorganic fillers are naturally-occurring or synthetic
materials such as quartz, nitrides (e.g., silicon nitride), glasses
derived from, for example Ce, Sb, Sn, Zr, Sr, Ba and Al, colloidal silica,
feldspar, borosilicate glass, kaolin, talc, titania, and zinc glass; low
Mohs hardness fillers such as those described in U.S. Pat. No. 4,695,251;
and submicron silica particles (e.g., pyrogenic silicas such as the
"Aerosil" Series "OX 50", "130", "150" and "200" silicas sold by Degussa
and "Cab-O-Sil M5" silica sold by Cabot Corp.). Examples of suitable
organic filler particles include filled or unfilled pulverized
polycarbonates, polyepoxides, and the like. Preferred filler particles are
quartz, submicron silica, and non-vitreous microparticles of the type
described in U.S. Pat. No. 4,503,169. Metallic fillers may also be
incorporated, such as particulate metal filler made from a pure metal such
as those of Groups IVA, VA, VIA, VIIA, VIII, IB, or IIB, aluminum, indium,
and thallium of Group IIIB, and tin and lead of Group IVB, or alloys
thereof. Conventional dental amalgam alloy powders, typically mixtures of
silver, tin, copper, and zinc, may also optionally be incorporated. The
particulate metallic filler preferably has an average particle size of
about 1 micron to about 100 microns, more preferably 1 micron to about 50
microns. Mixtures of these fillers are also contemplated, as well as
combination fillers made from organic and inorganic materials.
Fluoroaluminosilicate glass fillers, either untreated or silanol treated,
are particularly preferred. These glass fillers have the added benefit of
releasing fluoride at the site of dental work when placed in the oral
environment.
Optionally, the surface of the filler particles may be treated with a
surface treatment such as a coupling agent in order to enhance the bond
between the filler and the polymerizable resin. The coupling agent may be
functionalized with reactive curing groups, such as acrylates,
methacrylates, epoxies, and the like. Examples of coupling agents include
silanes such as gamma-methacryloxypropyl-trimethoxysilane,
gamma-mercaptopropyltriethoxysilane,
beta-(3,4-epoxycyclohexyl)ethyltrimethoxysilane,
gamma-glycidoxypropyltrimethoxysilane, and the like.
The materials of the present invention can also contain suitable adjuvants
such as accelerators, inhibitors, absorbers, stabilizers, pigments, dyes,
viscosity modifiers, surface tension depressants and wetting aids,
antioxidants, and other ingredients well known to those skilled in the
art.
The amounts and types of each ingredient in the dental material should be
adjusted to provide the desired physical and handling properties before
and after cure. For example, the cure rate, cure stability, fluidity,
compressive strength, tensile strength and durability of the dental
material typically are adjusted in part by altering the types and amounts
of polymerization initiator(s) and, if present, the loading and particle
size distribution of filler(s). Such adjustments typically are carried out
empirically based on experience with dental materials of the prior art.
When the dental material is applied to a tooth, the tooth can optionally be
pre-treated with a primer such as dentin or enamel adhesive by methods
known to those skilled in the art.
The invention is further described by reference to the following examples,
which are understood to be merely illustrative and not limiting the
invention in any way.
EXAMPLE 1
A stock resin solution ("SL1") of an epoxy resin and polyol containing
material was prepared by combining 0.50 g camphorquinone, 1.50 g
diphenyliodoniumhexafluoroantimonate (DPI SbF.sub.6) with 24.50 g UVR 6105
cycloaliphatic diepoxide and 0.50 g of polytetrahydrofuran diol having an
average molecular weight of 250 (pTHF-250) and stirring until homogeneous
in the absence of light. UVR 6105 is a cycloaliphatic diepoxide having the
following formula:
##STR5##
A variety of donor compounds were evaluated for their photoinduced
potential and ability to enhance cure speed. To evaluate the photoinduced
potential of the compounds, a stock initiator solution was prepared by
transferring 0.50 grams camphorquinone and 3.00 grams of DPI SbF.sub.6 to
a 250 ml polyethylene screw-top bottle. Two hundred grams of 99.5+%
2-butanone was transferred to the polyethylene bottle and the contents
mixed until homogeneous. The resulting solution contained approximately
2.9.times.10.sup.-5 moles DPISbF6/gram and 1.5.times.10.sup.-5 moles
CPQ/gram. The electron donor additives were evaluated at a concentration
of 2.9.times.10.sup.-5 moles donor/gram of SL1. Samples were prepared by
transferring 1.16.times.10.sup.-4 moles of donor to a 13 ml glass vial
followed by the addition of 4.0 grams of the stock initiator solution.
Vials were capped and vigorously shaken until homogeneous. Samples were
then evaluated for relative potential according to the following
procedure:
A semi-micro combination pH electrode (Corning model 476540) was connected
to a pH meter with millivolt capability (Beckman .PHI. P/N 123133). The
stock initiator solution was used as the millivolt standard in this
evaluation. Four grams of the stock initiator solution were transferred to
a 13 ml glass vial along with a micro-magnetic stir bar. The sample was
placed above a magnetic stirrer which initiated slow stirring of the
sample. The electrode was rinsed with water followed by ethanol and then
thoroughly dried with a paper towel. The electrode was immersed in the
stock initiator solution and the millivolt reading calibrated to read 0.00
mV. The electrode was removed and the sample was irradiated with a Visilux
dental curing light having an intensity of about 200 mW/cm.sup.2 at a
wavelength of 400 to 500 nm for 10 seconds by placing the tip of the light
guide directly flush with the center bottom of the vial. Following
irradiation the sample was capped and mixed thoroughly by shaking for
about 5 seconds. The electrode was rinsed, cleaned thoroughly with
ethanol, blotted dry and immersed in the irradiated solution. The
millivolts relative to the control was established by pressing the mV
button on the pH meter until a stable reading was obtained. The above
procedure was repeated with the various donor solutions. The electrode was
calibrated with unirradiated stock initiator solution before each run as
described previously.
The donor compounds were also evaluated for their effect on cure speed of
the stock resin solution. Approximately one gram samples were prepared by
transferring 2.9.times.10.sup.-5 moles of each prospective donor to 1 dram
glass vials followed by 1.0 grams of the stock resin solution. The
ingredients were mixed until homogeneous. Each sample was examined for gel
time by transferring the solution to a 6 mm diameter and 2.5 mm thick
Teflon mold with a polyester film clamped in direct contact with the
bottom face. The sample was placed directly beneath the light guide of a
Visilux 2 dental curing light at a distance of 10 mm. Samples were
irradiated and probed to establish hard gel times up to a maximum of 60
seconds. Results are reported in Table 1. Throughout the examples, "NC"
means that the material did not cure and "NT" means that the material was
not tested.
TABLE 1
Sample # Donor Compound gms donor/gm resin gel time (sec) mv
(initial) MEK mv (photo) MEK
1 None none 25 0
-25
2 4-dimethylaminobenzoic acid 0.0047 7 -11
184
3 ethyl 4-dimethylaminobenzaote 0.0053 7 -12
200
4 3-dimethylaminobenzoic acid 0.0047 12 -5
115
5 1,2,4-trimethoxybenzene 0.0053 7 -3 233
6 4-dimethylaminobenzoin 0.0068 9 -13.4 261
7 4-dimethylaminobenzonitrile 0.0045 16 (top) 9.7
266
8 4-dimethylaminobenzaldehyde 0.0043 16 (top) 8
245
9 4-dimethylaminophenethanol 0.0046 NC -83.2 17
10 dimethylaniline 0.0043 20 -55
54
11 2,5-dimethoxybenzylalcohol 0.0049 25 30.8
52
12 tetrahydrofurfuralalcohol 0.0030 25 -34
-10
13 1,2,3-trimethoxybenzene 0.0050 25 -1.9
5
14 1,3,5-trimethoxybenzene 0.0050 24 10.1
28
15 benzyl alcohol 0.0031 26 -13.7
24
16 2,4,6-pentamethylaniline 0.0050 22 10
71.3
17 N,N-dimethylbenzylamine 0.0040 25 -189.7
-170
18 triethanolamine 0.0042 NC -171
-162
19 dihydroxyethyl-p-toluidine 0.0058 NC -180
-98
20 4-t-butyl N,N-dimethylaniline 0.0050 34 NT
NT
EXAMPLE 2
A stock solution of an epoxy resin/polyol/acrylate resin material was
prepared by transferring 0.50 g camphorquinone and 1.50 g DPI SbF.sub.6 to
a glass jar followed by the addition of approximately 0.20 g of
dichloromethane solvent, 70.56 g of UVR 6105, 9.80 g of Ebecryl 1830
polyester hexacrylate (Radcure Specialties) and 17.64 g of pTHF-250. The
mixture was stirred until homogeneous in the absence of light.
Three donor compounds were evaluated for photoinduced potential and for
their ability to enhance the cure speed of the epoxy/polyol/acrylate resin
material.
To evaluate the photoinduced potential of the compounds, a stock initiator
solution ("SL2") was prepared by transferring 0.50 grams camphorquinone
and 3.00 grams of DPI SbF.sub.6 to a 250 ml polyethylene screw-top bottle.
Two hundred grams of 99.5+% 2-butanone were transferred to the
polyethylene bottle and the contents mixed until homogeneous. The
resulting solution contained approximately 2.9.times.10.sup.-5 moles
DPISbF6/gram and 1.5.times.10.sup.-5 moles CPQ/gram. The electron donor
additives were evaluated at a concentration of 2.9.times.10.sup.-5 moles
donor/gram of SL2. Samples were prepared by transferring
1.16.times.10.sup.-4 moles of donor to a 13 ml glass vial followed by the
addition of 4.0 grams of the stock initiator solution. Vials were capped
and vigorously shaken until homogeneous. Samples were then evaluated for
relative potential according to the procedure detailed in Example 1.
The donor compounds were evaluated for their effect on cure speed of the
epoxy/polyol/acrylate resin solution. Approximately one gram samples were
prepared by transferring 2.9.times.10.sup.-5 moles of each prospective
donor to 1 gram glass vials followed by 1 drop of dichloromethane solvent
and 1.0 grams of the stock resin material. The ingredients were mixed
until homogeneous. Each sample was examined for gel time by transferring
the solution to a 6 mm diameter and 2.5 mm thick Teflon mold with a
polyester film clamped in direct contact with the bottom face. The sample
was placed directly beneath the light guide of a Visilux 2 dental curing
light at a distance of 3 cm. Samples were irradiated up to a maximum of
120 seconds and probed to establish soft and hard gel times. Results are
reported in Table 2.
TABLE 2
gel
gms donor/ time Mv Mv
Donor Compound gm resin (sec) (initial) (photo)
none none 120 0 -25
4-dimethylaminobenzoic acid 0.0047 30 -11 184
ethyl 4-dimethylaminobenzoate 0.0053 35 -12 200
4-dimethylaminobenzoin 0.0068 70 -13 261
EXAMPLE 3
A bifunctional epoxy/acrylate material was prepared according to the
following procedure:
Epon 828 Bis Phenol-A-diepoxide (82.9 grams, 0.22 moles) was transferred to
250 ml three-necked resin flask which was fitted with a condenser, an air
driven stir rod with a Teflon stir blade and an addition funnel. The
system was kept dry with a calcium sulfate drying tube. The resin reactor
was partially immersed in an oil bath heated to about 100.degree. C. and
the diepoxide allowed to equilibrate to this temperature for about 30
minutes. Triphenyl antimony (1.1 grams) was transferred to the diepoxide
and allowed to dissolve for about 15 minutes. Methacrylic acid (17.2
grams, 0.20 moles) was weighed into the addition funnel and then slowly
added to the heated diepoxide slowly over about 3 hours. The mixture was
allowed to react for a total of 24 hours yielding a high viscosity liquid
which comprised a statistical mixture of monoepoxide/monomethacrylate
adduct and both diepoxide and dimethacrylate.
EXAMPLE 4
Two epoxy/acrylate polyol compositions were prepared from the reaction
product of example 3 as shown below with and without diphenyliodonium salt
(DPISbF.sub.6):
Sample 1 Sample 2
Ingredient Parts by Weight Parts by Weight
UVR6105 epoxy 64.00 64.00
Product of Example 2 20.00 20.00
pTHF-250 16.60 16.60
DPISbF.sub.6 0.00 1.50
CPQ 0.50 0.50
EDMAB 0.56 0.56
Samples approximately 2.5 mm thick were irradiated with a Visilux 2 Dental
curing light from a distance of about 10 mm for about 30 seconds. Both
samples were relatively soft and flexible and failed to register a BarCol
hardness value. Samples were transferred to an oven at 37.degree. C. for
24 hours. Sample 1 remained relatively soft whereas Sample 2 with
DPISbF.sub.6 was a hard solid with a barcol hardness value of about 30.
The data shows that the initial gelation is attributed to the free radical
polymerization from the reaction product of example 3 and subsequent
polymerization results from cationic curing of the epoxy resin UVR 6105
and reaction product of example 3, and that addition of the diphenyl
iodonium salt or compound provides cationic curing in addition to free
radical curing.
EXAMPLE 5
The effect of various diphenyl iodonium salts was evaluated in epoxy
resin/polyol compositions with and without the presence of an aromatic
amine. Three epoxy/polyol containing compositions were prepared as
follows:
Parts by Weight
Composition A(1)
UVR 6105 80.0
pTHF-250 20.0
Camphorquinone 0.50
DPI SbF.sub.6 1.50
Composition B(1)
UVR 6105 80.0
pTHF-250 20.0
Camphorquinone 0.50
DPI PF.sub.6 1.23
Composition C(1)
UVR 6105 80.0
pTHF 20.0
Camphorquinone 0.50
DPI Cl 0.90
Ethyl 4-dimethylaminobenzoate (EDMAB) was added to a portion of the above
compositions in an amount of 0.56 parts by weight per 100 parts of each of
A(1), B(1) and C(1), forming compositions A(2), B(2) and C(2)
respectively.
Each composition was prepared by combining the ingredients at room
temperature and stirring until homogeneous. Each composition was evaluated
for cure speed by irradiation of a 2 mm thick sample with light at a
wavelength of 400-500 nm from a Visilux 2 light source at a distance of 10
mm. Irradiation continued for 120s or until a soft or hard gel was formed.
Results are reported in Table 3.
TABLE 3
Composition Gel time (seconds)
A(1) 14
B(1) 16
C(1) NC
A(2) 8
B(2) 8
C(2) NC
This data illustrates that enhanced cure speed can be achieved when the
amine electron donor EDMAB is used in combination with an iodonium salt
with a .sup.-- PF.sub.6 or .sup.-- SbF.sub.6 counterion. No curing was
observed when .sup.-- Cl was the counterion, with or without the donor
EDMAB.
EXAMPLE 6
A variety of visible light absorbing sensitizers were evaluated in
epoxy/polyol formulations containing 1.50% Ph.sub.2 1SbF.sub.6, 0.50%
sensitizer compound and optionally 0.56% EDMAB by weight. Solutions A and
B, without and with EDMAB respectively were prepared as shown below:
Solution A Solution B
Ingredient Parts by Weight Parts by Weight
UVR6105 80.00 80.00
pTHF-250 20.00 20.00
DPISbF.sub.6 1.50 1.50
EDMAB -- 0.56
Sensitizers were evaluated by transferring 0.0050 grams of the sensitizer
to a 2 gram glass vial followed by the addition of 2 drops of
dichloromethane solvent and 1.0 grams of solution A. Compositions were
mixed until homogeneous and evaluated for gel time as described in example
1. The same procedure was repeated for solution B. Set out in Table 4 are
the run numbers, sensitizer and the gel times with and without EDMAB.
TABLE 4
Sample Gel time/no Gel time/
# Sensitizer Compound EDMAB EDMAB
(0.0050 gm/gm resin) (seconds) (seconds)
1 None NC NC
2 Camphorquinone 14 8
3 2-Chlorothioxanthone 25 (surface only) 15
4 Fluorenone NC 30 (top 1 mm)
5 Furil 115 40
6 Dibromofluorescein 70 17
7 Fluorescein 95 (surface only) 91 (surface only)
8 Ethyl Eosin 64 (surface only) 15
9 Eosin y 19 (surface only) 20
(complete cure)
10 Benzoylbenzocoumarin NC 15
11 Rose Bengal NC 26
12 Isopropylthioxanthone 11 (surface only) 20
(complete cure)
15 Anthraquinone 30 (surface only) 90
(complete cure)
16 Diethoxyanthracene 20 (surface only) 40 (surface only)
17 2-ethyl-9,10 22 (surface only) 45 (surface only)
dimethoxyanthracene
18 9,10 dichloroanthracene NC NC
19 Diphenyl isobenzofuran 32 41
20 Methylene violet NC NC
The data illustrates that a variety of ketone functional sensitizers in
combination with DPISbF.sub.6 and the electron donor EDMAB photocures
faster and/or more completely than those formulations with sensitizer and
DPISbF.sub.6 alone.
EXAMPLE 7
The effect of EDMAB to DPISbF.sub.6 molar ratio on gel time was examined.
Molar ratios of EDMAB/DPISbF.sub.6 ranging from 0 to 8.0 were
investigated. Solution A was prepared by combining 16.0 g UVR 6105, 4.0 g
pTHF-250, 0.10 g camphorquinone and 0.30 g DPISbF6. This solution
contained 2.9.times.10.sup.-5 moles of DPISbF.sub.6 per gram of resin.
Solution B was prepared by transferring 0.44 grams of EDMAB to a glass
vial followed by 10.0 grams of solution A resulting in a on containing
2.3.times.10.sup.-4 moles of EDMAB per gram of resin or 8 molar
equivalents of EDMAB/DPISbF.sub.6. 1 gram mixtures of Solutions A and B
were prepared and evaluated for gel time as described in Example 1,
however the irradiation distance was 10 mm. Set out in Table 5 are the run
numbers, grams of solutions A and B, the molar ratio of amine to onium
salt and the gel times.
The data illustrates that significant cure speed enhancement can be
achieved with as little as 0.08 equivalents of EDMAB relative to onium
salt. Optimal cure speed is achieved with approximately 0.10 to 1.0
equivalents. Further addition of EDMAB beyond 1.0 equivalents results in a
near linear increase in gel time (inhibition) and decrease in material
hardness.
TABLE 5
Grams Grams
solution B solution A Molar
2.32 .times. 10.sup.-4 2.0 .times. 10.sup.-5 Ratio
moles moles EDMAB/ Gel time
Sample # EDMAB/gm onium/gm Onium (seconds) Comments
1 0.00 1.00 0.00 18 hard solid
2 0.01 0.99 0.08 9 hard solid
3 0.02 0.98 0.16 7 hard solid
4 0.03 0.97 0.25 8 hard solid
5 0.05 0.95 0.40 8 hard solid
6 0.10 0.90 0.80 8 hard solid
7 0.20 0.80 1.60 13 hard solid
TABLE 5
Grams Grams
solution B solution A Molar
2.32 .times. 10.sup.-4 2.0 .times. 10.sup.-5 Ratio
moles moles EDMAB/ Gel time
Sample # EDMAB/gm onium/gm Onium (seconds) Comments
8 0.30 0.70 2.40 15 hard gel
9 0.40 0.60 3.20 20 hard gel
10 0.50 0.50 4.00 21 hard gel
11 0.60 0.40 4.80 25 soft gel
12 0.70 0.30 5.60 30 soft gel
13 0.80 0.20 6.40 35 soft gel
14 0.90 0.10 7.20 55 soft gel
15 1.00 0.00 8.00 60 soft gel
The data shows that the addition of the amine donor EDMAB can both enhance
and decrease the cure speed and properties based on low and high
concentrations, respectively, relative to the absence of EDMAB
EXAMPLE 8
Eighteen photocurable epoxy/polyol resin formulations were prepared with
the component concentrations as shown in Table 5 for a 2.sup.(5-1)
fractional factorial design experiment. The five experimental variables in
the study
A) % camphorquinone (CPQ),
B) % diphenyliodonium hexafluoroantiminate (DPISbF6),
C) % ethyl-4-dimethyl aminobenzoate (EDMAB),
D) ratio of aliphatic to cycloaliphatic diepoxides (EPON/UVR ratio),
E) % polytetrahydrofuran MW 250 (pTHF).
The aliphatic diepoxide used was diglycidyl ether of bisphenol A (Epon 828,
Shell Oil Co.); the cycloaliphatic diepoxide used was
3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate (UVR-6105).
Gel time of each of the prepared resin solutions was tested under
continuously irradiating of a Visilux-2 dental curing light. Three
millimeter thick cylindrical Teflon BarCol Hardness molds were filled with
uncured resin. The uncured resin in each mold was then irradiated at a
distance of 1 cm with a Visilux-2 dental curing light while being
frequently probed with a plastic mixing stick. The time in seconds at
which the resin began to thicken and exhibit properties of a soft solid
was recorded as gel time. The average of three such tests for each resin
formulation is tabulated in Table 6 alongside the corresponding
compositional information for each resin formulation.
The statistical analysis (YATES ANOVA) indicates that EDMAB was a
statistically significant variable with an average effect of 7.7 seconds
reduction in gel time when 1 molar equivalent (based on DPISbF6) is added
to the resin formulations.
TABLE 6
VISIBLE LIGHT CURED EPOXY FORMULATIONS
WITH DPISbF.sub.6 IN EPOXY/POLYOL RESIN
Resin Variables 2(5-1) Fractional Factorial
Variable (-) 0 (+)
% Camphorquinone Sensitizer 0.25% 0.50% 0.75
% DPISbF6 (CD-1012) Catalyst 0.50% 1.00% 2.00%
EDMAB (DPISbF6 Electron (0 eq.) (0.5 eq.) (1 eq.)
equiv.) donor
EPON 828:UVR-6105 Epoxy resins 1:2 1:1 2:1
Ratio
% Polytetrahydrofuran Polyol 10% 20% 30%
1 equiv. EDMAB = Grams DPISbF6 (193/516)
mol. wt. mol. wt. DPISbF6 =
EDMAB = 193 516
WEIGHT PERCENT OF COMPONENTS IN
ACTIVATED RESIN
EPON pTHF GEL
DESIGN CPQ DBISbF6 EDMAB 828 UVR6105 (250) TIME
ORDER (grams) (grams) (grams) (grams) (grams) (grams) (seconds)
1 0.25 0.50 0.00 23.08 46.17 30.00 14.3
2 0.75 0.50 0.00 29.58 59.17 10.00 24.0
3 0.25 2.00 0.00 29.25 58.50 10.00 46.0
4 0.75 2.00 0.00 22.42 44.83 30.00 14.0
5 0.25 0.50 0.19 29.69 59.37 10.00 12.6
6 0.75 0.50 0.19 22.85 45.71 30.00 11.0
7 0.25 2.00 0.75 22.33 44.67 30.00 18.0
8 0.75 2.00 0.75 28.83 57.67 10.00 13.3
9 0.25 0.50 0.00 59.50 29.75 10.00 37.3
10 0.75 0.50 0.00 45.83 22.92 30.00 23.0
11 0.25 2.00 0.00 45.17 22.58 30.00 23.6
12 0.75 2.00 0.00 58.17 29.08 10.00 39.0
13 0.25 0.50 0.19 46.04 23.02 30.00 30.6
14 0.75 0.50 0.19 59.04 29.52 10.00 17.6
15 0.25 2.00 0.75 58.00 29.00 10.00 26.6
16 0.75 2.00 0.75 44.33 22.17 30.00 30.0
17 0.50 1.00 0.19 39.15 39.16 20.00 11.3
18 0.50 1.00 0.19 39.16 39.15 20.00 11.3
Response: GEL TIME
VAR VARIABLE UNITS -1 LEVEL +1 LEVEL
A CPQ % 0.250 0.750
B DPISbF6 -0.301 0.301
C EDMAB 0.000 1.000
D 828:UVR 0.333 0.666
E pTHF % 10.000 30.000
STANDARDIZED SUM OF
VARIABLE COEFFICIENT EFFECT SQUARES
OVERALL 22.42
AVERAGE
A -2.32 -4.64 86.0
B 2.51 5.01 100.5
C -3.84 -7.69 236.4
D 4.66 9.31 346.9
E -3.24 -6.49 168.4
AB 0.08 0.16 0.1
AC 0.33 0.66 1.8
AD 1.26 2.51 25.3
AE 1.26 2.51 25.3
BC -0.49 -0.99 3.9
BD -1.17 -2.34 21.9
BE -1.67 -3.34 44.6
CD 1.58 3.16 40.0
CE 5.68 11.36 516.4
DE 1.58 3.16 40.0
CENTER POINT -12.51 278.1
EXAMPLE 9
(Preparative Example)
200.3 grams of deionized water was weighed into a 1000 ml rigid poly beaker
and adjusted to a pH of 3.02 with trifluoroacetic acid (Aldrich Chem. Co.,
Milwaukee, Wis.). 9.9099 grams of 3-glycidoxypropyltrimethoxysilane
(United Chemical Technologies, Inc., Bristol, Pa.) was slowly added to the
water while stirring with a magnetic Teflon coated stirring rod. About 50
ml of denatured ethanol was used to rinse the silane addition beaker, and
then added to the hydrolyzing aqueous silane solution. The solution was
allowed to stir for about 65 minutes (hydrolysis time) and then 200 grams
of a 90/10 weight blend of ball mill ground mined quartz, average particle
size 2.25-3.15 microns (3M Co., Maplewood, Minn., PMC-41-5300-0422-9) and
a commercially available fumed silica, Aerosil OX-50 (Degussa Inc.,
Frankfurt, GE) was slowly added to the silane treatment solution. The
resulting slurry was stirred for 27 hours at room temperature. The slurry
was then divided evenly among three 1000 ml poly beakers each beaker
placed in a convection drying oven for 12 hours at 60.degree. C. The dried
cake from each beaker was recombined, mortar and pestled, and then screen
in a sealed container on a shaker through a 74 micron nylon screen. The
screened powder was then placed in a one pint jar and dried for a final
time for 2 hours at 80.degree. C. After a short cool down the jar was then
sealed with a metal cap with foil lined paper seal to reduce the moisture
vapor transmission into or out of the jar.
EXAMPLE 10
This example describes the preparation of epoxy/polyol resin-based
composite materials containing an iodonium salt, an alpha-diketone and an
optional amine electron donor (EDMAB).
Two compositions were prepared as follows:
Composition A
UVR 6105 8.00 g
pTHF250 2.00 g
DPI SbF6 0.15 g
Camphorquinone (CPQ) 0.05 g
Total 10.20 g
Composition B
UVR 6105 8.00 g
pTHF250 2.00 g
DPI SbF6 0.15 g
CPQ 0.05 g
EDMAB 0.05 g
Total 10.20 g
Each composition was prepared by combining the ingredients at room
temperature and stirring until homogeneous.
Two composite materials were further prepared by combining 7.50 grams of
the filler from Example 9 with 2.50 grams of Compositions A and B
respectively. Samples were spatulated until a thick homogeneous paste was
obtained
Composite A
Composition A 2.50 g
Filler from Example 9 7.50 g
Total 10.00 g
Composite B
Composition B 2.50 g
Filler from Example 9 7.50 g
Total 10.00 g
Samples were evaluated for photopolymerization by determining the BarCol A
hardness of 2 mm thick sample according to the following procedure. A 2 mm
thick Teflon block which had a cylindrical hole with a diameter of about 6
mm that extended through the thickness of the block was placed on a film
of transparent polyethylene terephthalate (PET) such that one end of the
of the open cylindrical hole of the die was covered by the PET film. The
Teflon die was filled with the sample and another film of PET placed on
top of the die covering paste sample. Hand pressure was applied to the PET
film to provide an approximately 2 mm thick sample. samples were
irradiated with the Visilux 2 light source for 30 seconds by placing the
light wand directly on the PET film which covered the sample at the top of
the die. Five sets of samples were prepared in triplicate and stored at
for 5 minutes, 20 minutes and 24 hours at 25.degree. C. and 20 minutes and
24 hours at 37.degree. C. respectively after storage, the PET films were
removed and the BarCol hardness of the top and bottom of the die was
measured using a Barber-Coleman Impressor (a hand-held portable hardness
tester; Model GYZJ 934-1; from Barber Coleman Company Industrial
Instruments Division, Lovas Park, Ind.) equipped with an indenter. For
each sample tested, three readings were taken at the top and bottom of
each sample. The readings were averaged for each composition and storage
condition. A hardness value of zero indicated limited or no
polymerization. Bottom hardness values significantly less than those of
the top indicate limited depth of cure. Results are summarized in Table 7
below:
TABLE 7
Barcol Hardness
25.degree. C. 37.degree. C.
Side 24 24
Sample Tested 5 min. 20 min. hours 20 min. hours
Composite A Top 48 58 67 66 70
(no EDMAB) Bottom 18 40 67 62 67
Composite B Top 54 54 56 64 56
(EDMAB) Bottom 52 53 63 67 63
The data shows that Composite B which contains the donor EDMAB exhibits
greater top and bottom hardness when post-cured for 5 minutes at
25.degree. C., compared to Composite A without EDMAB. This illustrates
that the co-catalyst EDMAB significantly enhances the rate of curing of
the epoxy/polyol composite.
EXAMPLE 11
This example describes the preparation of epoxy/polyol/methacrylate
resin-based composite materials containing an iodonium salt, an
alpha-diketone and an optional amine electron donor.
Two compositions were prepared as follows:
Composition A
UVR 6105 7.20 g
pTHF250 1.80 g
Ebecryl 1830 1.00 g
DPISbF6 0.15 g
Camphorquinone 0.05 g
Total 10.20 g
Composition B
UVR 6105 7.20 g
pTHF250 1.80 g
Ebecryl 1830 1.00 g
DPISbF6 0.15 g
Camphorquinone 0.05 g
ethyl-p-dimethylaminobenzoate 0.05 g
Total 10.25 g
Each composition was prepared by combining the ingredients at room
temperature and stirring until homogeneous.
Two composite materials were further prepared by combining 7.50 grams of
the filler from Example 9 with 2.50 grams of Compositions A and B
respectively. Samples were spatulated until a thick homogeneous paste was
obtained
Composite A
(no EDMAB)
Composition A 2.50 g
Filler from Example 9 7.50 g
Total 10.00 g
Composite B
(EDMAB)
Composition B 2.50 g
Filler from Example 9 7.50 g
Total 10.00 g
Samples were evaluated for photopolymerization by determining the BarCol A
hardness of 2 mm thick sample according to the procedure described in
Example 9. Results are summarized in Table 8 below.
TABLE 8
Barcol Hardness
25.degree. C. 37.degree. C.
Side 24 24
Sample Tested 5 min. 20 min. hours 20 min. hours
Composite A Top 45 39 66 58 70
(no EDMAB) Bottom 0 0 58 17 59
Composite B Top 47 54 64 60 64
(EDMAB) Bottom 37 53 64 59 59
The data shows that Composite B which contains the donor EDMAB exhibits
significantly greater bottom polymerization when post-cured for 5 or 20
more minutes at 25.degree. C. or 20 minutes at 37.degree. C., compared to
Composite A without EDMAB. The electron donor EDMAB provides enhanced cure
speeds for thick sections of epoxy/polyol/acrylate composites.
EXAMPLE 12
Dental restorative pastes were prepared from each of the five light curable
epoxy/polyol resin formulations shown in Table 8. The filler for each was
prepared from a blend of 95 wt % finely milled P-10.TM. quartz filler
(.sup..about. 3 micron APS) and 5 wt % fumed silica OX-50 (Degussa Inc.).
The two silica based filler were blended in a 1000 ml beaker, then slurred
overnight in a 3-3.5 pH hydrolyzed aqueous solution of 5% (based on filler
weight) 3-glycidoxypropyltrimethoxy silane. The slurry cake was dried at
60.degree. C. for 12 hours, crushed and screened through a 74 micron nylon
screen. After a final drying of 80.degree. C. for two hours the filler was
band spatulated into the resins in 8-10 gram batch sizes to either 82.0%
or 82.5% filler weight loading.
The resulting pastes were then tested for compressive strength and
diametral tensile strength after irradiation with two Visilux-2 dental
curing lights for 80 seconds in 1/8" ID Lexan tubing and after a post cure
of 24 hours in 37.degree. C. distilled water.
TABLE 9
LIGHT CURED EPOXY FORMULATIONS
WITH DPISbF6 IN EPOXY/POLYOL RESIN
Compressive Diametral
WEIGHT OF COMPONENTS PER 100 GRAM Strength Tensile Wt. %
EPON UVR- pTHF (MPa) (MPa)
Silane
CPQ DPISbF6 EDMAB 828 6105 (250) 24 hr. 24 hr.
treated
(grams) (grams) (grams) (grams) (grams) (grams) (n = 5)* (n = 5)*
Quartz
0.75 0.50 0.00 30.00 60.00 10.00 247 (10) 69.5 (1.8)
82.0
0.25 0.50 0.00 60.0 30.00 10.00 233 (11) 60.7 (8.6)
82.0
0.75 2.00 0.75 53.33 26.67 20.00 259 (7) 70.2 (5.0)
82.0
0.50 1.00 0.19 42.50 42.50 15.00 262 (6) 75.6 (1.7)
82.0
0.50 1.00 0.19 42.50 42.50 15.00 312 (7) 82.7 (9.4)
82.5
*Numbers in ( ) are standard deviations of 5 test values (n).
EXAMPLE 13
(Preparative Example)
A bifunctional aliphatic epoxy/acrylate material was prepared according to
the following procedure:
UVR 6105 Cycloalophatic diepoxide (109.6 grams, 0.44 moles) was transferred
to 250 ml three-necked resin flask which was fitted with a condenser, an
air driven stir rod with a Teflon stir blade and an additional funnel. The
system was kept dry with a calcium sulfate drying tube. The resin reactor
was partially immersed in an oil bath heated to about 100C and the
diepoxide allowed to equilibrate for about 30 minutes. Triphenyl antimony
(0.3 grams) was transferred to the diepoxide and allowed to dissolve for
about 15 minutes. Methacrylic acid (8.6 grams, 0.11 moles) was weighed
into the addition funnel and then slowly added to the heated diepoxide
slowly over about 3 hours. The mixture was allowed to react for a total of
24 hours yielding a liquid somewhat higher in viscosity than the starting
materials. The bifunctional epoxy/acrylate material therefore had about
one fourth (1/4) of the epoxy functionalities reacted with the unsaturated
acid. The resulting resin is referred to hereinbelow as "UVR 1/4."
EXAMPLE 14
This example describes the preparation of twenty-one epoxy/methacrylate
resin-based composite materials containing varying amounts of UVR 1/4
(described in example 13). UVR6105 (cycloaliphatic diepoxide), pTHF250
(aliphatic diol), HPMA (3-hydroxypropyl methacrylate), DPISbF.sub.6 (an
iodonium salt), CPQ (camphorquinone--an alpha-diketone) and EDMAB
(ethyl-p-dimethyl aminobenzoate--an amine electron donor).
Twenty-one resin compositions were prepared as follows shown in Table 10.
Each composition was prepared by combining the ingredients at room
temperature and stirring until homogeneous.
Twenty-one composite materials were further prepared by combining 3.0 grams
of the quartz filler OX-50 with 6.0 grams of Compositions in Table 10
respectively. Samples were spatulated until a thick homogeneous paste was
obtained.
Samples were evaluated for photopolymerization by determining the BarCol A
hardness of 2 mm thick sample according to the following procedure. A 2 mm
thick Teflon block which had a cylindrical hole measuring about 6 mm
diameter that extended through the thickness of the block was placed on a
film of transparent polyethylene terphtalate (PET) such that one end of
the open cylindrical hole of the die was covered by the PET film. The
Teflon die was filled with the sample and another film of PET placed on
top of the die covering paste sample. Hand pressure was applied to the PET
film to provide an approximately 2 mm thick sample. Samples were
irradiated with the Visilux 2 light source for 60 seconds by placing the
light wand directly on the PET film which covered the sample at the top of
the die. Three sets of samples were prepared in triplicate and stored for
10 minutes and 24 hours at 25C and 24 hours at 37.degree. C. respectively.
After storage, the PET films were removed and the hardness of the top and
bottom of the die was measured using a Barber-Coleman Impressor (a
hand-held portable hardness tester; Model GYZJ 934-1; from Barber Coleman
Company Industrial Instruments Division, Lovas Park, Ind.) equipped with
an indenter. For each sample tested, three readings were taken at the top
and bottom of each sample. The readings were averaged for each composition
and storage condition. A hardness value of zero indicated limited or no
polymerization. Bottom hardness values significantly less than those of
the top indicate limited depth of cure. Results are summarized in Table 10
below.
TABLE 10
Barcol
Hardness Testing
Composition of Samples 10 min RT
24 hr RT 24 hr 37 C.
Sample # UVR 1/4 UVR6105 pTHF250 HPMA CPQ DPISbF.sub.6 EDMAB
top/bottom top/bottom top/bottom
a 1.82 7.58 0.50 0.10 0.05 0.125 0.01
33/0 66/56 44/33
b 7.58 1.62 0.50 0.10 0.05 0.125 0.01
0/0 36/24 52/46
c 1.54 6.38 1.74 0.34 0.05 0.125 0.01
53/52 59/50 37/55
d 6.38 1.54 1.74 0.34 0.05 0.125 0.01
57/53 57/54 57/59
e 1.82 7.58 0.33 0.26 0.05 0.125 0.01
62/57 40/57 63/62
f 7.58 1.82 0.33 0.26 0.05 0.125 0.01
0/0 47/19 56/56
g 1.52 6.38 1.15 0.93 0.05 0.125 0.01
48/32 54/48 57/57
h 6.38 1.53 1.15 0.93 0.05 0.125 0.01
27/26 51/32 58/56
I 4.29 4.30 0.99 0.47 0.05 0.125 0.01
17/0 55/51 52/58
j 4.29 4.30 0.93 0.47 0.05 0.125 0.01
38/19 53/46 59/61
k 4.29 4.30 0.93 0.47 0.05 0.125 0.01
20/0 51/43 58/57
l 4.29 4.30 0.93 0.47 0.05 0.125 0.01
16/0 52/50 59/58
m 0.00 8.80 0.93 0.47 0.05 0.125 0.01
55/45 53/60 63/61
n 6.60 0.00 0.93 0.47 0.05 0.125 0.01
0/0 43/44 55/57
o 5.00 5.00 0.00 0.00 0.05 0.125 0.01
0/0 26/17 51/49
p 3.77 3.77 1.64 0.82 0.05 0.125 0.01
52/30 54/53 59/59
q 4.30 4.90 1.40 0.00 0.05 0.125 0.01
55/50 52/56 57/57
r 4.30 4.30 0.70 0.70 0.05 0.125 0.01
0/0 41/43 55/53
s 4.30 4.30 0.83 0.47 0.05 0.125 0.01
18/0 44/95 54/54
t 4.30 4.90 0.99 0.47 0.05 0.125 0.01
34/28 39/39 57/54
u 0.00 8.00 2.00 0.00 0.05 0.125 0.01
63/54 61/62 65/63
This example demonstrates that compositions containing bifunctional
epoxy/acrylate materials and/or difunctional epoxy materials, and
optionally containing hydroxy functional acrylates, together with polyols,
provide resins that exhibit desirable cure properties. These compositions
exhibit either good initial cure properties or demonstrate a "living" cure
system by hardening over time after initial exposure.
The above specification, examples and data provide a complete description
of the manufacture and use of the composition of the invention. The United
States patents referred to in the foregoing specification are incorporated
into the specification by reference. Since many embodiments of the
invention can be made without departing from the spirit and scope of the
invention, the invention resides in the claims hereinafter appended.
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